Fuel delivery apparatus for injection internal combustion engines



stilt 0- H. HElNRlCH ETAL 2,215,755

FUEL DELIVERY APPARATUS FOR INJECTION INTERNAL COMBUSTION ENGINES FiledApril 14, 1938 2 Sheets-Sheet l H. HEINRICH ET AL. 2,215,756 FUELDELIVERY APPARATUS FOR INJECTION INTERNAL COMBUSTION ENGINES 2Sheets-Sheet 2 Filed April 14, .1938

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Patented Sept. 24, 1940 PATENT OFFICE FUEL DELIVERY APPARATUS FOR INJEC-TIO N INTERNAL COMBUSTION ENGINES Hansl Heim-ich and Johann FriedrichJanssen, Stuttgart, Germany, assignors to Robert Bosch GeselischaIt mitbeschriinkter Haftung, Stuttgart, Germany Application April 14, 1938,Serial No. 202,052 In Germany April 29, 1937 7 Claims.

The present invention relates to fuel delivery hand pump which isoperated before the engine 5 is started to fill up all thechambers andpipes which convey fuel to the engine and wherein air which is displacedon manual pumping to the space between a non-return or back pressurevalve and an overflow valve by-passes the overfliow valve and isdischarged into the overflow P D Since the non-return or back pressurevalve provided at the outlet of the suction chamber of the injectionpump opens the passage to the space between the two-valves when a flowcommences from the suction chamber in a direction towards the spacebetween the valves, it'is possible, on manual pumping, for fuel to passinto the space between the two valves and flll'this space before all theair has been drawn out of the suction chamber of the injection pump.

Now in order to ensure the undisturbed withdrawal of all the airaccumulating in the suction chamber during filling up with fuel, theby-pass of the overflow valve according to the present invention, offersno resistance worth mentioning to the air displaced, on hand pumping,from the suction chamber which has not yet been filled with fuel, but,on the other hand, oilers such a high resistance to the discharge offuel, especially'to the discharge, towards the space between the twovalves, of the fuel delivered in excess during the running of the enginethat the pressure in the suction chamber can become large enough to openthe overflow valve.

The invention is more particularly described 7 with reference to theaccompanying drawings which show three forms of construction by way ofexample and inwhich:

Figure 1 is a diagrammatic view of the layout of a fuel delivery plantwith an air separator, the casing enclosing non-return or .back pressurevalve and the overflow valve being shown in longitudinal section.

Figures 2 and 3 show in horizontal sections through the non-return andoverflow valves the second and third forms of construction.

In the construction according to Figure 1 a multi-cylinder injectionpump is connected by "pressure pipes 2 to the injection nozzles (notshown) of an internal combustion engine. A

fuel supply container 3 remote from the injection plant is connectedthrough cut-oil cocks B with two delivery pumps 4, which take fuel fromthe container in all operating positions through the pipe 4a by means ofa pivoted pipe to. Each of the two delivery pumps 4 delivers somewhatmore fuel than is taken at full load setting from the suction or inletchamber la, of the multi-cylinder injection pump. In the right handsuction pipe la. of the delivery pump 4 there is disposed a hand orother manually operated pump H. The suction pipe 411 of the deliverypump 4 is in communication through a pipe 41) with the pressure pipe 5.In the pipe 4b is disposed a reverse pumping valve open towards thepressure pipe 5 and having small preliminary tension. The pres-; surepipe 5 opens into an air separator 6, the inner chamberof which isconnected through the pipe I with the suction chamber la of theinjection pump. v

At the highest point the suction chamber Ia which is remote from themouth of the pipe 1, an overflow pipe 8 branches oil into a valve casing9, the internal space of which is divided by a separating wall 90 intoleft and right hand chambers 9a, 9b. A pipe ll branching oif from thehighest point of the chamber 9b leads back to the supply container 3.

in and on that side of The overflow pipe 8 of the suction chamber In ofthe injection pump projects into the chamber 9a of the casing 9, and atits point of outlet into this chamber there is arranged a non-return orback pressure valve 12, the spindle of which is guided in a ring l3provided with passage openings. A weak spring H tends to keep thenonreturn valve'closed.

In the wall 90 separating the two chambers 90 and 9b there is provided asecond opening which an overflow valve 15 tends to keep closed. Thepressure at which thevalve l5 opens is determined by the tensioning of aspring l6, which abuts on an externally adjustable screw II.

In the upper part of the separating wall 90, there is provided a smallthrottle bore l0, which by-passes the over-flow valve IS. A pipe Illinterconnects the upper partof the air separator 6, and the upper partof the chamber 9a of the valve casing 9. With this arrangement, thehighestpoint [0a of the pipe in is situated above the highest point oithe suction chamber in. of the injection pump. In the upper portion ofthe wall of that end of the pipe 8 projecting into the chamber 9a, thereis provided a narrow throttle bore 8a.

In the manual pumping operation the level of fuel in the pipe 4 and inthe suction chamber In, ziniformly with that in the pipe Ill. Since thehighest point of the suction chamber is situated lower than the highestpoint of the pipe ill,

the suction chamber first fills up completely, before the pipe Ill hasbeen filled with fuel. The air displaced from the suction chamber duringthis filling can flow away through the throttle bore 8a 'and I8 withoutany resistance worth mentioning. As soon as the suction chamber has beenfllled with fuel however, then, on continuation of hand pumping, thefuel level also rises, in the pipe Illa, until finally fuel flows boththrough the non-return valve l2 and the pipe I 0, Illa. into the chamber9a, and displaces the air enclosed therein towards the pipe ll throughthe throttle element l8. Only when the chamber So has been completelyfilled with fuel, does the delivery pressure of the hand pump riseconsiderably, and enable the complete removal of air I from all thespaces in the fuel system to be recognized.

The resistance which that part Illa of the pipe lll,-which is situatedabove the highest point in the suction chamber, during operation opposesthe escape of air from the separator is substantially smaller than thatresistance which the excess fuel overflowing from the suction chamber ofthe injection pump towards the chamber 911 encounters by virtue of thethrottle 8a and the non-return valve l2.

After the fuel pipe system has been freed from air, the internalcombustion engine is started up. When the engine is running,. thedelivery pumps 4 force fuel in excess of requirements through the pipe 1towards the suction chamber la of the injection pump. From there, thesuperfluous portion of the fuel flows into the chamber 9a as soon as thepressure reached in the suction chamber is able to open the non-returnvalve l2. From there, together with the air flowing out of the separatorthrough the pipe II], it flows back through the overflow valve l5, whichis previous ly tensioned to suit-the desired pressure in the suctionchamber of the pump, and through the pipe ll back to the container.

In order to eliminate the possibility on the operation of the internalcombustion engine, of the two delivery pumps 4 forcing the main part ofthe delivery amount into the chamber 9a through the by-pass l0 insteadof through the suction chamber la and the non-return valve l2, 9.throttle element l9 may be provided in the pipe III as a substitute foror as an addition to the resistance in the pipe, effected by the higherportion Illa thereof.

In the modification according to Figure 2, a hollow hexagonal nipple 20is screwed in a threaded bore lb, on the side of the pump casing of theinjection pump andopening at the highest point of the suction or inletchamber l a, the axial bore 2l of which nipple is somewhat narrowedatthe point where it is screwed into the bore lb. In the axial bore 2|there is accommodated a non-return valve 22, for which the constrictedbore of the hexagonal nipple provides a seat. A spring 23 tending topress the non-return valve on to the seating formed by the constrictedbore abuts against a ring 24 provided in the other end of the axialbore, which ring is maintained in position by a snap ring 25. Thenon-return valve itself is longitudinally bored, 8. section of whichlongitudinal bore is constructed as a narrow throttle 26. In a taperedand wider section of this longitudinal bore is accommodated a ball valve21, which is prevented from falling out of the longitudinal bore by across pin 28.

Over the free, externally threaded, end, of the hexagonal nipple 20,there is pushed the central part, which is extended to form a boss, of apipe 29, which is secured by a screw cap 30 to the hexagonal surface ofthe nipple 20. The interior of the pipe 29 is connected by cross bores3| with the axial bore of the nipple 20. The axial bore of the righthand branch of the pipe 29 contains the overflow valve 32, which istensioned by a spring 33, in the same manner as the non-return valve 22.The spring tends to press the valve 32 on to the constricted axial boreof the right hand portion of the pipe 29. In a longitudinal bore in theoverflow valve 32, there is provided as in the case of the valve 22, avery narrow throttle 36. To the right hand branch of the pipe, there isattached a flexible pipe 31 leading to the supply container 3. To theleft hand branch of the pipe there is attached one end of anotherflexible pipe 38, of which the other end is attached to the upper partof the air separator 6.

When the pipe system is being filled up by means of the hand pump, theair driven out of the suction chamber of the injection pump opens thesmall ball valve- 21, so that the air is conducted through the throttlebore 26 of the closed non-return valve 22 towards the axial bore 2| inthe nipple, and from the latter, together with the air escaping from theseparator through the flexible pipe 38, through the throttle bore 36 ofthe valve 32, which is likewise closed at this stage, and thence towardsand through the flexible pipe 31. During runningof the engine thenon-return valve 22, which has been pre-tensioned to a relatively smallpressure, and the overflow valve 32 which is pre-tensioned to arelatively higher pressure, have the same action as the correspondingvalves in the construction shown in Figure l, which together maintainthe pressure in the suction chamber at the desired height. As soon as aflow directed towards the suction chamber is likely to commence from theflexible pipe 38 conveying the air from the separator, the ball 21closes the throttle element 26, so that no accumulation of air in thenipple 20, can reach the suction chamber of the injection pump.

The example shown in Figure 3 differs from pipe 29 for the flexiblepipes 31, 38 firmly on the nipple and seals it. The part of the pistondirected towards the suction chamber is axially bored at 42, from whichthere leads a throttle 43 which is in communication with a radial bore44 in the piston which extends to its outer periphery. In the positionof the piston as shown the bore 3| provided in the wall of the nipple20a is situated'opposite to the outlet point of the radial bore 44. Awide cross bore 45 branching off from the axial bore 42 in the pistonopens belowthe radial bore 44 of the piston, and inthe position shown iscovered by the inner wall of the nipple 200.

When the manually operated pump is being used, the air pushed out of thepipes and out of the suction chamber, in that position of the piston asshown wherein the spring is substantially relaxed, passes through thebores 42, 43, 44 into the pipe 29, from where it can reach the supplycontainer 3 through the throttle bore 36 of the overflow valve. As soonas all the air has been driven outof the suction chamber by the fuel,and the pressure in the suction chamber is rising, the piston 40 israised against the action of the spring, and the throttle 43 is coveredby the inner wall of the nipple 2|. ,When the delivery pumps areoperated during running of the engine, then should the pressure in thesuction chamber rise to the full working pressure the bore 45 will openso that fuel can flow from the suction chamber to the supply container.

In contrast with the example in Figure 1, the pipe l0 may likewise bemade. to open into the lower part of the chamber -9a, and the elevatingof the pipe (see Illa) above the highest point of the suction chamber lamay thus be discarded,

if a non-return valve is arranged in the pipe Ill.

If there were no throttle element IS, the opening pressure of this valvewould have to be so proportioned asv to be larger than the resistancewhich the throttle member 8a in Figure 1 or 26 in Figure 2, or 43, H inFigure 3, opposes to the eiiiux of air from the suction chamber on handpumping. On the other hand, however, the opening pressure of this valvewould have to be smaller than the resistance which the throttle member8a, or 26 or 43, 44, respectively, together with the non-return valve l2(Figure l), or 22 (Fig-' ure 2), or 40 (Figure 3), respectively opposesto the discharge of the superfluous fuel from the suction chamber.

We declare, that what we claim is:

1. The combination, in a fuel delivery apparatus for internal combustionengines, comprising a delivery pump, an injection pump, an air separatordisposed therebetween, a pipe line through which air-freed fuel isconveyed from said separatorto an inlet chamber of the injection pump, amanually operated pump, a supply container, and a pipe connectionpermitting delivery of fuel by said delivery pump or said manuallyoperated pump from said supply container to said overflow valve and arestricted connection dis posed in said return system between thejunction of said second pipe therewith and said supply container, saidoverflow valve being more strongly pretensioned than said non-returnvalve, said restricted connection by-passing said overflow valveand'offering substantially no resistance to the flow of air but offeringrelatively high resistance to the flow of fuel, and a restricted by-passfor the non-return valve which offers substantially no resistance to theflow of air but which offers a relatively high resistance to the flow offuel.

2. The combination as set out in claim 1 including an additionalnon-return valve located in said restricted by-pass for the firstnon-return valve which opens at the smallest increase of pressure insaid inlet chamber in front of the restricted by-pass as compared withthe pressure in the space in rear thereof.

3. The combination as set out in claim l wherein the restricted by-passis disposed in a movable which the fuel encounters on its way throughthe inlet chamber of the injection pump towards the space situatedbetween the non-return and overflow valves.

5. The combination as set out in claim 1 wherein the separator islocated in a position lower than the inlet chamber of the injectionpump, and wherein a section of the second pipe connecting the airseparator and the space between the non-return and overflow valves isdisposed higher than the highest point of the inlet chamber of theinjection pump and of the feed pipe thereof.

6. The combination, in a fuel delivery apparatus for internal combustionengines, comprising a fuel delivery pump, an auxiliary manually operatedfuel delivery pump, a fuel supply container, an air separator, pipingpermitting delivery of fuel by said pumps from said supply container .tosaid air separator, an injection pump having a fuel inlet chamber, and apipe connected to the lower part of said air separator and leading tothe inlet chamber of said injection pump, of a I return conduitconnecting said inlet chamber with said supply container for return flowof superfluous quantities of fuel from said inlet chamber to said supplycontainer, a second pipe beginning in the upper part of said airseparator and leading into said return conduit, said second pipe having'a higher'resistance to flow of fuel than said first pipe and inletchamber, a non-return valve arranged in said return conduit between thesupply container and the junction of said second pipe with said returnconduit, said non-return valve opening in the direction of return flowof fuel'in said return conduit, a restricted connection in said returnconduit which by-passes said nonreturn valve and which offers arelatively high resistance to the flow of fuel but substantially noresistance to the flow of air, and a passage which meets the upper partof the inlet chamber with said return conduit, said passage having arestricted cross-section which offers arelatively high resistance to theflow of fuel but substantially no resistance to the flow of air.

'7. The combination, in a fuel delivery apparatus for internalcombustion engines, comprising a fuel delivery pump, an auxiliarymanually operated fuel delivery pump, a fuel supply container, an airseparator, piping permitting delivery of fuel by said pumps from saidsupply container to quantities of fuel from said inlet chamber to saidsupply container, a second pipe beginning in the upper part of said airseparator and leading into said return conduit, said second pipe havinga higher resistance to flow of fuel than said first pipe and inletchamber, a non-return valve arranged in said return conduit between thesupply container and the junction of said second pipe with said returnconduit, said non-return valve nects the upper part of the inlet chamberwithsaid return conduit, and a non-return valve in said passage andwhich opens in the direction of return flow of fuel in said returnconduit, said second non-return valve being very weakly loaded ascompared to the loading of the first-mentioned 5 non-return valve.

. HANS JOHANN FRIEDRICH JANSSEN.

